What is a particulate filter?
The particulate filter is a filtration device that is located on the exhaust side (after combustion), being designed to retain the particles emitted by the engine up to 0.01 μm, it can be located before or after the catalyst, or between the two catalysts. .
Placing the particulate filter before the catalyst favors obtaining the temperature necessary for its regeneration. Its efficiency is between 95 - 100%, thus considerably reducing the emissions of unburned and ash particles from the gases, these particles being directly harmful to humans, they are easy to inhale, remain in suspension and attach to the lung walls, being carcinogenic.
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In general, they are found only in diesel engines, being called DPF (diesel particulate filter), but lately they have appeared for Otto engines, but being rare, and this in direct injection engines, being called GPF (gasoline particulate filter ). With the Otto engine, soot emissions are much lower (several dozen times), making this system unnecessary.
For Diesel engines, the first vehicles equipped with DPF appeared starting with the Euro 4 pollution norms, and starting with the Euro 5 pollution norms (2009 in the European Union) they are mandatory for all compression ignition engines.
Starting with Euro 6 pollution norms, for vehicles that do not meet the exhaust gas treatment conditions to comply with the low limits imposed by this standard, and if the mass of the vehicle exceeds 1700 kilograms, in addition to the particulate filtration system the car must be equipped with a catalyst with Adblue.
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There are two types of particulate filters: dry and additive-based (Ad-blue or Eolys).
There are cars equipped with larger particle filters, they differ from one engine to engine ,corresponding to the engine cylinder capacity, and since the filter is disposable every 150,000 km it must be replaced because it gets clogged and no longer functions properly. Other cars that have regenerative particle filters have the advantage of a longer life (under normal operating conditions they can exceed 200,000 km), the cleaning being done thermally by burning the deposits inside.
There are cars that have an additional injector before the DPF, the deposits being thermally dissolved and removed. There are also ones that can regenerate the particulate filter on the spot, the engine speed being between 1400 and 1600 rotations per minute for a few minutes.
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Lifetime of a particulate filter and operating conditions
The lifespan of a particulate filter would be between 100,000 - 250,000 km, these values vary depending on the operating conditions, rarely being able to exceed 350,000 km.
Thus, the life of a particle filter depends on the driving style (short and frequent roads are not beneficial, typical of urban operation), the type of fuel used, engine oil, injectors / common fuel ramp, problems on the air intake side, problems with pressure sensors when the EGR valve has problems (being clogged / defective), worn engine components or turbocharger (being out of parameters / worn / defective) that can burn the oil.
Why is the particulate filter clogged?
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For a car equipped with a diesel engine, especially those equipped with DPF from the factory, it is recommended to be operated mostly in extra-urban mode (shuttles, etc.), where the engine always reaches the optimum operating temperature, it heats up. it is heavier than gasoline engines, so urban driving and the use of the vehicle at low speeds favor the clogging of the particulate filter.
What do you need to do to regenerate the particulate filter or DPF?
If it is used mainly in urban regime, for a long health of the particle filter and implicitly of the engine, it is recommended that once every 2 to 4 weeks to make a longer trip outside the city, of about 80-100 km, at a speed of over 2500 revolutions per minute and with a constant speed of about 60 km / h, until the indicator corresponding to the regeneration of the filter disappears.
The particulate filter must withstand temperatures up to 700 - 1000 ° C, this value can be achieved when a command is given by the ECU that regulates the amount of fuel that reaches the engine, creating a rich mixture of fuel that can not be burned completely in combustion processes, so the temperature of the particle filter rises very much, which favors the cleaning of the particles left in the filter. It usually takes about 10 to 20 minutes.
Types of particulate filter regenerations
Active regeneration is triggered by temperature sensors and sensors that determine the exhaust gas pressure (before and after the filter) or for those with a single sensor that is located before the filter which calculates the difference between the flue gas pressure and atmospheric pressure thus estimating the degree of filter loading.
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Passive regeneration is given by certain car manufacturers, it occurs during longer trips , when the exhaust gas temperature reaches the optimum temperature for regeneration, this regeneration being unnoticed by the driver of the car (also called spontaneous regeneration).
There is another type, called forced regeneration, this being a more special case, and it is triggered by automatic regeneration failed attempts to clean the particulate filter, and so you can opt for its forced regeneration.
The ECU can thus trigger idle regeneration, increase engine load and speed, and reduce the air-fuel ratio, thus having a rich fuel mixture.
Manual regeneration is quite dangerous, it is done from the tester, the particulate filter can catch fire because the temperatures reach high levels and the vehicle being at idle does not receive enough air and does not cool properly, the risk of fire is high because the situation can degenerates to parts immediately following the particle filter.
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To enter the regeneration mode of the particulate filter, the conditions that must be met by the engine are to reach a minimum value of the exhaust gas temperatures, and the engine speed must have a minimum value for a certain gas flow. When the dpf regeneration indicator appears, it is recommended not to stop the engine but actually increase the speed
Why choose chemical cleaning of the particulate filter?
If we think logically, it is the most viable option. New diesel cars clean their particle filter with AdBlue, which is a special chemical to clean the filter. So if you have a car that does not have AdBlue you can use other special cleaning products.
An example of a product would be Liqui Moly 5171 DPF Cleaner. All the products we find on the market now are almost the same, the name is the one that differs, each with a different manufacturer. But there is only one thing that matters, the substances you find are special for cleaning the particle filter and they even do their job.
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Many cancel their particle filter or even replace it. A big mistake. Canceling it will void the warranty (if you still have it) and risk large fines and you must avoid controls and you will not pass the inspection at ITP. Why do owners cancel or change their filter? Simple. Because it gets clogged. It is normal for the particle filter to clog, but this does not mean that it must be canceled or changed. It is filled with soot but this soot can be cleaned very easily using chemical cleaning.
Advantages of chemical cleaning of the particle filter
dissolve any type of deposit on the filter
decreases fuel consumption
improves engine performance
Why are diesel cars equipped with a particulate filter?
The particulate filter (DPF) is a filter that captures and stores soot from the exhaust. It was first mounted on diesel cars, only on diesel, in 2009, with the introduction of Euro 5 standards. Since 2009 all new cars, diesel, had to have particulate filters fitted.
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The particulate filter can only store a limited amount of soot, so it must regenerate. Many say that diesel cars should not be driven in the city if we want the filter to regenerate .Why? Because the car cannot start its regeneration cycle in the urban environment, due to the driving style. Regeneration is done only at a certain temperature. The car must be kept running for a longer period of driving, which is impossible in the city. During regeneration the soot is practically transformed into soot but with a granulation, if you allow us, smaller, soot which is then more easily eliminated and less toxic.
Symptoms of a clogged DPF
Usually the electronic control unit (ECU) communicates to us when it needs regeneration, so a yellow indicator light appears on the board
If it does not regenerate, various errors will be shown on board depending on the vehicle, the warning light corresponding to the regeneration will light up or warn us audibly, not being taken in regeneration it will be blocked irremediably, reaching failure mode, also called limp mode, in this way the vehicle no longer revs , the power and torque will be reduced , the speed being limited to a maximum of 3000 revolutions per minute, a value that varies from one manufacturer to manufacturer
When the particulate filter gets clogged, other problems usually occur, we will have a rich mixture of fuel, thus increasing consumption with rich combustion, automatically increasing soot emissions.
The filter can fail prematurely if it collects too many particles,when it does it can be cleaned only with specific procedures at specialized workshops.When it gets clogged, is removed from the vehicle, a special chemical fluid is used. The parameters are measured before cleaning followed by the main cleaning process in a specially arranged space and at the end a comparative test report is needed
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Particulate filter replacement
If the particulate filter has reached the end of its life cycle, it must be replaced or cleaned. To be replaced with a new one, the prices for it vary between 1000 - 4000 euros. The price is very high, since it has a honeycomb structure with porous walls (storing smoke and ash particles here) that contains silicone ceramics that block the particles emitted by the engine.
The price being so high many give it up completely, being a crime that is supported by many services that offer services to cancel the particle filter starting with 200-300 euros. If the physical cancellation is done, it is recommended to do the software cancellation as well, so the ECU will consider that the particle filter works perfectly even though it is no longer physically there, this whole process can be done within a few hours.
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For the engine, this is beneficial because it will no longer encounter additional resistance, but will emit a much larger amount of particles and smoke, harmful to humans and the environment.
What is the on-board indicator of the DPF or particulate filter?
Depending on the car manufacturer, the warning light may be different, but in the picture below you have all the common options.
In conclusion, we advise you to choose the car according to your own needs, do not choose the car according to the advice of friends and in no case just like it. Choose a diesel car only if you have to drive a lot with it and in extra-urban areas, it makes no sense to choose a diesel car if you live in a city with heavy traffic.
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You will end up paying a lot more money for maintenance than you would save on fuel.
I forgot to specify, but for French cars, DPF is FAP. The particle filter can be abbreviated as follows: DPF and FAP.
Photo source: rac.co.uk, donotdpfdelete.green, dackmotorgroup.co.uk, dpfcentre.com, youtube.com
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